A new organization consisting of hundreds of Republican delegates is raising money to stop Donald Trump from winning his party’s nomination.

Referring to their movement as “Free the Delegates,” these Republicans are pushing for the adoption of a “conscience clause” at the 2016 Republican National Convention. This rule would allow delegates to vote for whomever they wish, regardless of which candidate won during the primaries.

Now that organization has launched a website, FreeTheDelegates.com, on which visitors are urged to enter their contact information so their state’s Rule Committee member will be sent information about the movement. The website is not currently taking donations, but they are expected to soon begin raising money for a staff and legal defense, according to The Hill.

Last week, a conference call was held for members of the Free the Delegates group during which about 30 delegates were present. According to The Washington Post, a second call held on June 19th consisted of several hundred participants.

Donald Trump fired back at this Free the Delegates movement on Saturday, saying that stealing the nomination from him would be illegal.

“First of all, it’s meaningless. Second of all, it’s illegal. Third of all, you can’t do it,” Trump said at a Las Vegas rally.

Trump also accused former presidential candidate Jeb Bush of working with the Free the Delegates organization, although the group’s website says it is not paid for by any candidate or candidate’s committee.